He wrote: "Thanks Dinamo Zagreb for everything!! My first club and biggest love!! Now is time to move on to Barcelona."

The transfer was confirmed on Thursday morning, though, via an official club statement, which gave more details about the terms of the arrangement.

“FC Barcelona has reached an agreement with Dinamo Zagreb and Alen Halilovic for the transfer of the player to the club for an initial amount of 2.2 million euros, which will increase as the player achieves the objectives of consolidating a position in the first team,” the statement read. “The player, who turns 18 on June 18, will start out in Barca B. Halilovic has signed a contract for five seasons.”

Zoran Mamic, who works as coach and sporting director of Dinamo, told his club’s official website: “Of course we’re happy to have agreed such a big deal not only for our club but Croatian football in general.

“It’s also great news that Alen will be staying with us until the end of the season, and I’m sure that the fans will enjoy his performances in the months ahead.”

Halilovic said he wanted to finish the campaign on a high with Dinamo and added: “Of course, Barcelona are something special -- a club I have loved since I began playing football -- and I am very honoured and very happy to get the chance to wear the shirt of the Catalan giants.”

Despite being just 17, Halilovic has already made 19 appearances for Croatian top-flight leaders Dinamo, scoring three goals, while he has also featured in the Champions League.

In June 2013, he became the youngest-ever senior Croatia international when making his debut in a friendly against Portugal, and is line to go to this summer’s World Cup as a back-up squad member.

The youngster’s displays in an attacking midfield position have already led to comparisons with national captain Luka Modric, with clubs including Manchester City, Manchester United, Tottenham and Real Madrid having reportedly sent scouts to watch him in action for Dinamo earlier this season.